Setting and visualizing a virtual camera and lens system in a computer graphic modeling environment

ABSTRACT

A virtual camera and lens system in a three dimensional computer graphic modeling environment is set using a nominal focal length and a focus distance. A true focal length is calculated. An optical axis object that represents the optical axis of the virtual camera and lens system is created in the three dimensional computer graphic modeling environment. An object is attached to the optical axis at a location that visualizes the setting of the virtual camera and lens system as determined from the true focal length. The focal length of the virtual camera and lens system is set to the calculated true focal length. The focus distance and f-stop may be determined from near and far focus points.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/957,063 filed Oct. 1, 2004, now U.S. Pat. No. 7,428,482, which is acontinuation-in-part of application Ser. No. 09/276,883, filed Mar. 26,1999, abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The system and method of the present invention relates to threedimensional computer graphic modeling, and more particularly to settingand visualizing parameters of a virtual camera in a three dimensionalgraphic model to control later photorealistic rendering by a computer.

2. Background

The use of computers to generate photorealistic three dimensional imageshas become widespread. Computers frequently are used to generate and/ordisplay three-dimensional images, pictures and moving images such asvideo and movies. Animation using the computer is quite common. Theseimages are generated a variety of ways. For instance, an image may becomputer generated through software executing on the computer. At othertimes real world images are imported from another media, such as film ora camera and lens apparatus electrically connected to the computersystem. Computers also are being used to combine real world images andcomputer generated images.

Production of photorealistic images from three dimensional computergraphic models may be very time consuming, possibly taking several hoursto produce a single image. The production of photorealistic images maybe split into a modeling phase and a rendering phase. Artists may buildand manipulate the graphic models in the modeling phase which may beoptimized for real-time interaction. The modeling phase may produce adescription of the scene that is passed to the rendering phase where thephotorealistic images are produced without artist involvement.

The production of even a single photorealistic image may not be feasiblein real-time. In particular, the generation of photorealistic movingimages in real-time is extremely difficult. Artists preparingphotorealistic three dimensional images often work with simplifiedrepresentations of the scenes they are preparing. For example, an artistmay work with wireframe models in which objects are represented bymeshes of lines that only suggest the size and shape of an object. Inother cases, previsualizations may be generated that show the appearanceof objects but simplifying or omitting most of the subtle photographiceffects to reduce the time and/or computing power required to generatethe previsualization images. The fully rendered image is generated onlyafter the scene has been completed based on the use of the simplifiedpresentations of the computer model. Since the rendering of the finalphotorealistic three dimensional images may be time consuming andcostly, it is desirable that the artists preparing the scene achieve thedesired result before the final image is rendered.

A digitally simulated virtual camera may be part of the computer graphicmodel to control the rendering of the three dimensional model as a twodimensional photorealistic image. The rendering of a computer generatedimage may be controlled by the virtual camera. The virtual cameraprovides parameters such as position, orientation, and lens settingsequivalent to the parameters of a physical camera and lens system. Therendering software may use some or all of the camera parameters toachieve photorealism of the final rendered images. For example, therendering software may use the focus setting of the virtual camera'slens to determine what objects will be rendered in sharp focus and whichwill appear blurred to suggest being out of focus. The artist may adjustthe parameters of the virtual camera—such as focus, focal length, andaperture—to achieve the desired photographic effect. It will beappreciated that all apparent optical effects of the virtual camera areentirely the result of computation performed by the rendering softwareand there are no real optical effects involved in the rendering process.

Modern photographic camera equipment and lenses contain a number offixed and adjustable elements or parameters that may be modeled by therendering software and affect the appearance of the final renderedimages. The film gate (sometimes referred to as the aperture) representsa horizontal and vertical dimension of the image being exposed onto thephotographic film or, in the case of the video camera, the size of thevideo image recording chip. The f-stop (sometimes also referred to asthe aperture) on the lens controls the amount of light striking the filmgate. The focal length of the lens identifies the distance from the rearnodal point of the lens to the surface of the focal plane. The focusrepresents a distance in front of the camera. The field of view is thearea photographed by the lens and contains the images captured throughthe lens. The circle of confusion provides a measure of image clarity orsharpness of focus for a point. A camera typically has a focus ring tocontrol focus from a setting of infinity to distances typically in therange of two to three feet. On a zoom lens a second control exists tomanipulate the focal length.

The settings of these different features may be expressed usingdifferent scales and units. For example, the focal length typically isexpressed in millimeters. The film gate (aperture) typically isexpressed in thousandths of an inch. The actual film stock in theaperture typically is referred to in millimeters. The f-stop is alogarithmic scale based on light transmission through the lens. Thefocus is typically set in feet, or sometimes in inches or meters. Thefield of view is typically expressed as an angle of degrees eitherhorizontal, vertical or diagonal. In addition, the relationship betweenthe horizontal and vertical dimensions of the aperture, referred to asthe aspect ratio, is represented as a single number assumed to be aratio to a value of 1. Motion picture examples include 1.33:1, 1.66:1,1.85:1, 2.20:1, 2.35:1. These typically are referred to as “1.33”,“1.66”, “1.85”, “2.20”, “2.35”; which represents how wide the formatappears to be to the viewer in relation to the image height. Inaddition, the circle of confusion is typically measured in thousandthsof an inch.

A typical 3D software modeling package does not provide a preview of theeffects of virtual camera lens adjustments. Some 3D software modelingpackages, such as those marketed by SOFTIMAGE, an Avid Corporation, Inc.company, provide control of the lens characteristics such as f-stop,focus, and the circle of confusion. However, the lens characteristicsprovided are used strictly for the creation of the photorealisticcomputer graphic image as the final step in the simulation process.

When objects are defined within a computer graphics softwareenvironment, a camera object is usually specified solely in order toprovide a particular view of those objects. Since the system is anelectronic simulation and does not use light rays or an optical systemto capture and record the image, physical real world issues like focusdo not come into play. Instead the images are viewed by the user on thecomputer system or recorded out to a picture file. For example, allobjects in a preview computer graphics image may be shown as though allobjects were in perfect focus.

For these reasons, computer graphics images are normally sharp duringthe interactive phase when the images are generated and combined withother images, as the images presented to the user during that phase donot take lens characteristics into account. Typically an attempt tosimulate the effects of focus and other lens artifacts are applied aspart of a separate and last rendering step in the creation of a finalcomputer graphic image, i.e., subsequent to the interactive phasecontrolled by the artist.

The computer modeling environment used by the artist may not provideadequate feedback of lens values, or determinations of exact boundariesor locations of lens effects. Furthermore, the calculations typicallyused to derive the final field of view for a particular lens in a 3Dmodeling package contains assumptions, omissions, oversights andoversimplifications of the real world equivalent true lens and cameracombinations. Most notable are the lack of solving for the effects ofchange in focus as it relates to focal length and the lack of equivalentcontrols compared to a real world camera. The relationship among lensattributes, such as focal length, focus and f-stop are not wellunderstood or implemented in current software packages and do notsuccessfully address the problems and details of simulating the changesin these optical characteristics. To appreciate this, consider that anominal 100 mm lens focused at 2 ft. has a true focal length of nearly120 mm.

Effects, such as the changing of focal length as a lens is focused, areobscured to the observer by the pronounced effects of blurring as theobject goes in and out of focus. In the situation where matching a realworld environment to a computer-generated object is not exact, thesituation is oftentimes only fixed through trial and error and a usermay need to guess tolerances and measurements as an approximation toregenerate a combined image multiple times to see what “looks best.”

In addition, currently available 3D software modeling packages do notcontain some of the features common to many real world cameras, such asinterchangeable reference clips and direct and interactive control offocus, zoom values and depth of field. These missing elements constituteimportant technical considerations for getting the exact lens setting asclose as possible to the settings of the real world camera and for beingable to operate a computer graphics virtual 3D camera in the same mannerand ease as a real world camera.

The virtual camera and lens system and method of the present inventionaddresses the setting and visualization of the settings, prior torendering, of a computer graphic, virtual, three dimensional camera andlens model having the variables and features of a real world camera andlens device.

SUMMARY OF THE INVENTION

A virtual camera and lens system in a three dimensional computer graphicmodeling environment is set using a nominal focal length and a focusdistance. A true focal length is calculated. An optical axis object thatrepresents the optical axis of the virtual camera and lens system iscreated in the three dimensional computer graphic modeling environment.An object is attached to the optical axis at a location that visualizesthe setting of the virtual camera and lens system as determined from thetrue focal length. The focal length of the virtual camera and lenssystem is set to the calculated true focal length. The focus distanceand f-stop may be determined from near and far focus points.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is an overview of one embodiment of the system of the presentinvention.

FIG. 1 b is a simplified block diagram of a desktop computer system thatoperates in accordance with the teachings of the present invention.

FIG. 2 is a flow diagram illustrating the input, computations and outputof one embodiment of the method of the present invention.

FIGS. 3 a and 3 b are simplified flow diagrams illustrating theembodiments of processes for adjusting camera and lens parameters inresponse to a camera and lens parameter changes.

FIGS. 4 a and 4 b are simplified flow diagrams illustrating embodimentsof a process for generating a computer generated image in the field ofview of a camera modeled according to camera and lens characteristics ofa real world camera and lens.

FIG. 5 is a simplified flow diagram of a process for determining cameraand lens characteristics in accordance with the teachings of the presentinvention.

FIG. 6 a is a flow diagram illustrating the processes utilized in oneembodiment of the system and method of the present invention and FIG. 6b is a table illustrating parameters and variables utilized.

FIG. 7 is a flow diagram that illustrates the infinity cutoff decisionprocess in one embodiment of the system and method of the presentinvention.

FIG. 8 a is a perspective view illustrating one embodiment of thecomponents of camera and lens system in accordance with the teachings ofthe present invention.

FIG. 8 b is a perspective view illustrating one embodiment of thecomponents of the camera and lens system of the present invention.

FIG. 8 c is a camera lens point of view showing the different camera andlens parameters in one embodiment.

FIG. 8 d is a top view illustrating the camera and lens parameters inone embodiment.

FIG. 9 a is one embodiment of a top view illustrating the field of viewof a camera and lens system in accordance with the teachings of thepresent invention.

FIG. 9 b is one embodiment of a perspective view of the camera and lensparameters illustrated by FIG. 9 a.

FIG. 9 c is one embodiment of a camera view with superposed 3D chartsand objects in accordance with the teachings of the present invention.

FIG. 9 d is one embodiment of a camera view showing a 3D reference chartand objects without the superposed grid as illustrated in FIG. 9 c.

FIG. 10 a shows a top view of an alternate embodiment of a display ofcamera and lens parameters in accordance with the teachings of thepresent invention.

FIG. 10 b provides a perspective view of FIG. 10 a.

FIG. 10 c shows a camera view of the camera and lens parameters inaccordance with the teachings of the present invention.

FIG. 11 a shows an alternate embodiment of a display of camera and lensparameters in perspective in accordance with the teachings of thepresent invention.

FIG. 11 b shows a top view illustrating the field of view of oneembodiment of the present invention illustrated b FIG. 11 a.

FIG. 11 c shows a camera view of a 3D reference chart and objectscorresponding to FIG. 11 a.

FIG. 11 d shows the camera view of FIG. 11 a including 3D referencechart, objects and a superposed grid.

FIG. 12 a is a top view of an alternate embodiment of a display ofcamera and lens parameters in accordance with the teachings of thesystem of the present invention.

FIG. 12 b is a top orthographic view of the parameters illustrated inFIG. 12 a.

FIG. 12 c is a camera view of FIG. 12 a illustrating an object andreference chart.

FIG. 13 a is a top orthographic view illustrating an alternateembodiment of a display of a camera and lens field of view in accordancewith the teachings of the present invention.

FIG. 13 b is a camera view illustrating 3D reference chart and objectsof FIG. 13 a in accordance with the teachings of the present invention.

FIG. 14 a is a top orthographic view showing the field of view inaccordance with the teaching of the present invention.

FIG. 14 b is a camera view showing a reference chart and objects inaccordance with the teachings of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The setting and visualization of a virtual camera and lens system of thepresent invention, in one embodiment, operates in a three dimensionalcomputer graphic modeling environment to provide numeric and visualfeedback of camera and lens parameters and to adjust the virtual cameraso that later rendering will more closely match the results that wouldbe produced by a corresponding real camera. The visualization systemautomatically updates related camera and lens parameters when changesare made to one or more camera and lens parameters such that theresulting renderings more accurately resemble the results produced byreal optical systems. The invention provides numeric and 3D visualfeedback of lens characteristics to help the user predict and visualizelens characteristics before rendering of the graphic model takes place.It also provides a visualization and presentation of lens data in aninteractive fashion, including characteristics that are difficult orimpossible to see in real world or typical computer graphicpresentations.

Furthermore, the system of the present invention can determine cameraand lens parameter values in an interactive fashion without requiringburdensome computations. Thus, the system is capable of receiving datato define a setting of a real camera and lens in the form used to setthe real camera and then setting parameters of the virtual camera asrequired to provide a closely matching rendering. The system may be usedto recreate and visualize a specific setting from a particular realcamera and lens after an image to be matched has been captured throughnormal photographic or electronic camera and lens systems. Thus,computer generated images can be matched to real world images takenthrough a camera and lens device without the unsightly artifacts thatoccur when real world and computer generated images are combined usingprior art systems that do not provide visualization of the effects ofthe settings of the virtual camera to allow the real and virtual camerasto have consistent settings.

In the following description, for purposes of explanation, numerousdetails are set forth in order to provide a thorough understanding ofthe present invention. However, it will be apparent to one skilled inthe art that theses specific details are not required in order topractice the present invention.

An overview of one embodiment of the system of the present invention isillustrated in FIG. 1 a. A processing system 42 receives input eitherthrough user input 40 or external input 41, such as may come from acamera and lens device. The system performs certain steps to providenumeric and/or visual feedback reflective of the lens and cameraparameters of a virtual camera and lens as defined at least in part bythe input. In one embodiment, the steps performed by the processingsystem are determined from instructions stored on media, such as amemory or storage device or received across a transmission media; theseinstructions are executed by processing system 42.

In the present embodiment, the digitally simulated camera softwaremodule 44 is interfaced with a three dimensional (3D) software modelingmodule 43 such as one produced by SOFTIMAGE, an Avid Corporation, Inc.company. Specially developed 3D software that generates 3D images on adisplay and the corresponding numeric values also may be used.

The processing system 42 provides a monitor display 46. In oneembodiment, the monitor display 46 is embodied in a desktop or notebookcomputer system, an example of which is illustrated in FIG. 1 b, andprovides images as seen through the digital camera and lens system aswell as other views of the graphic model. The monitor display 46 mayinclude values that indicate camera and lens parameters, which mayinclude values set by the user and derived values determined from suchsettings.

FIG. 2 is a flow diagram illustrating further the operation of oneembodiment of the system and method of the present invention. Inparticular, in the present embodiment, the input 50, which may bereceived from a user or from a physical device, may include suchparameters as camera orientation data, lens attributes, film format andinserted reference objects.

For example, camera orientation input data may include the XYZtranslational position of the virtual camera in space, as well as thepan, tilt and roll attributes of the virtual camera at any particularspatial position. The term “pan” relates to the y axis rotation of thecamera, producing a horizontal sweep effect of a scene, a “tilt” relatesto an x axis rotation of the camera, producing a vertical sweep of ascene, and “roll” relates to a z axis rotation, producing a rotationalor spinning effect of a scene.

The camera film format input includes the film gate (aperture) size,which may be expressed as the width of the film gate, and aspect ratio,which is the ratio of the width to the height of the film gate. The lensattributes may include the focal length, desired circle of confusion,focus setting, f-stop and infinity setting cutoff setting. In addition,reference objects can be input, such as clips, charts and visual aids,to assist the user in performing filming functions. As will be explainedbelow, as parameters are input and/or modified, other parameter settingsare updated correspondingly to provide an indication of the effects of arealistic and accurate camera and lens system.

To provide this functionality, a number of calculations may beperformed, such as shown in block 55, including true focal length, truefield of view and hyperfocal distance, depth of field, near focus limitand far focus limit, aspect ratio, and film gate (aperture) setting.

A lens may be identified by a nominal focal length which is the distancefrom the middle of the lens to the point where parallel rays enteringthe lens will converge. When a lens is focused on an object at a finitedistance in front of the lens, the lens is advanced away from the pointof convergence. Thus the true focal length of a lens is a function ofthe focus distance with the true focal length being longer than thenominal focal length when the lens is focused to a finite focusdistance.

Rendering engines calculate the two dimensional image that would resultfrom “photographing” the three dimensional model using the modeledvirtual camera. The rendering engine models many of the optical effectsinherent in the virtual camera to produce a photo-realistic twodimensional rendering. When the rendering engine uses the nominal focallength to determine things such as field of view, depth of focus, andother rendered features that are affected by the focal length of thevirtual lens, the rendering may not closely match the results that wouldbe produced by a real camera and lens system having the same settings asthe virtual camera. The focal length of the virtual camera may bedynamically set to the true focal length by the invention so that therendering will more closely match the corresponding results that wouldbe obtained from a real camera and lens system.

Depth of field represents the range of distances from the camera withinwhich objects will be considered acceptable sharp for photographicpurposes. Depth of field can be specified as a “near focus plane” and a“far focus plane” with the actual focus point itself being somewhere inbetween these two areas. Anything between these two planes will beconsidered “in focus” as defined by the circle of confusion setting,which defines the maximum acceptable size of a point source in thefocused image.

Hyperfocal distance represents a special case of depth of field in whichobjects at infinity, as well as the nearest possible objects, arephotographed with acceptable sharpness. When the lens is focused on thehyperfocal distance, the depth of field extends from half the hyperfocaldistance to infinity. Therefore, if a lens is focused at the hyperfocaldistance, all the image points between one-half the hyperfocal distanceand infinity will not exceed a specific circle of confusion. One-halfthe hyperfocal distance is defined as the hyperfocal focus.

Correct horizontal and vertical angles of the field of view aredetermined from the true focal length. The system also uses the truefocal length to determine correct placement of reference objects andcorrect placement of camera and lens attribute markers for display on amonitor or other device 60.

A real camera captures a two dimensional image of a three dimensionalscene. In a real camera, the lens forms an optical image on the filmplane. The film gate optically masks the outer part of the image so thata rectangular image is exposed on the film. In some real cameras thefilm gate may be larger than the portion of the image that will be usedand the effective film gate is applied at a later point in theduplication of the camera footage. In other real cameras, anamorphiclenses may be employed to squeeze a wider image onto a narrower filmframe. As used here, the term film gate or aperture is used to mean theeffective film gate that represents the boundaries of the undistortedimage that will be displayed in the final presentation.

In a real camera, a viewfinder is provided to show the camera operatorthe image that will be exposed on the film. The viewfinder may providefor insertion of a clip that shows the boundaries of the film gate ofthe camera. A clip is a reference object that indicates the outerboundaries of what will be included in the final rendered image asdetermined by the film gate (aperture). The viewfinder is designed to beoptically equivalent to the film plane. Therefore the clip is opticallyequivalent to the film gate. If the viewfinder image is the same size asthe image on the film plane, a common arrangement in real cameras, thenthe clip is a rectangle that is the same size as the film gate. All theoptical effects that affect the image as formed on the film plane, suchas changes in focal length, are accurately displayed in the viewfinderrelative to the clip.

In a graphic modeling environment, the virtual camera is merely arepresentation of the parameters that will be used by the renderingengine to calculate a two dimensional image of the three dimensionalscene created by the graphic model. The virtual camera does not providea viewfinder. To provide the guidance of a clip in the viewfinder of areal camera, the invention may provide a clip in the form of arectangular frame placed in the scene in a way that allows therelationship of the modeled scene to the boundaries of the finalrendered two dimensional image to be visualized. As discussed below, theclip for the virtual camera must be adjusted as the virtual cameraparameters are adjusted so that the clip always maintains the correctrelationship to the scene as it will be rendered.

Reference objects are similar to clips. While clips show the outerboundary of the two dimensional image, reference objects show theposition of objects within the two dimensional image. For example, ifthe images being generated by the computer graphic model are to becomposited with existing live footage, there may be an object in thelive footage that needs to interact with an object being modeled. Areference object may be created showing where the existing object iswithin the frame of the live footage. The reference object is then usedto guide the placement of the objects in the computer graphic model sothat the rendered footage will relate properly to the live footage.Reference objects have to be adjusted as the virtual camera parametersare adjusted in the same manner as clips so that the reference objectalways maintains the correct relationship to the scene as it will berendered.

FIG. 3 a is a simplified flow diagram illustrating one embodiment of themethod of the present invention. At step 305, camera and lens parametersare input. In the present embodiment, the parameters that can be inputinclude those set forth in FIG. 2. The data input can be received from adevice such as a real world camera and lens, a computer generatedvirtual camera and lens device, or a media device which stores ortransmits input data values. A media device includes, but is not limitedto, memory, data storage device, a computer system, external device, auser via a user input device (e.g., through keyboard or cursor controldevice and a graphical user interface), or a wired or wireless networkincluding local area network and the Internet.

At step 310, if a change of a lens parameter is detected, such as achange of focus, then at step 315 other pertinent lens parameters areadjusted in response to the lens parameter change. As a specificexample, in one embodiment, when the focus is changed there is a changein the true focal length of the lens. In turn, all the attributes thatrelate to the focal length are changed. These include the depth offield, the hyperfocal distance, the hyperfocal focus and the angles offield of view. In addition, objects used to indicate or locate theseeffects are also shifted accordingly. Alternately, if there is no changein input camera and lens parameters, or if an input parameter changedoes not offset other parameters, the process continues and is set toaccept new input camera and lens parameter data.

Another embodiment is illustrated in FIG. 3 b. At step 320 camera andlens parameters are input. True camera and lens parameters aregenerated, step 325, based upon the input. Markers or charts can beenabled/input to the system to be viewed by the user, step 330.

These markers include markers defining near focus and far focus or otherparameters such as the actual position of the hyperfocal focus, positionof the hyperfocal distance, position of the focus itself and theposition of the near and far limits of focus (depth of field). Thesystem of the present invention may be configured to output thesepositions as distances or locations. Other types of markers and chartssimulate the optically produced effects of mechanical or physicalversions in a real camera as part of the comprehensive lens and camerasimulation of the system of the invention.

Thus, if at step 335 a camera and lens parameter is changed, at step 340pertinent camera and lens parameters are updated and at step 345 markersand charts are updated if necessary to provide a consistent view to theuser such as would be viewed if a physical marker or chart ismechanically attached to a camera and lens device.

In another embodiment, as illustrated in FIG. 4 a, a virtual camera canbe modeled, enabling the simulation of a camera and lens system. At step410, the characteristics of a camera and lens are input. This input mayor may not be reflective of an actual real world camera and lens device.At step 415 a model of a digitally simulated model of the virtual cameraand lens is generated based upon the input camera and lenscharacteristics. At step 420 a computer generated image in the field ofview of the modeled camera and lens or data representative of the sameis generated.

In this embodiment, the system can be used to compute camera and lensparameters while filming with a real camera for correct adjustment ofthe real camera and lens device for subsequent use in a computergenerated camera and lens system, or to generate a true display of animage according to the camera and lens parameters input. In thissituation, the system can be used to predict, visualize or define asituation with the camera and lens before actual photography takesplace. Thus, the system eliminates guesswork and a search for propervalues when looking through a viewfinder while providing instantaneousupdates as values are changed.

In another embodiment, as illustrated in FIG. 4 b, the invention may beused after a real world image has been photographed with a real cameraand lens system in order to better integrate the computer graphicsgenerated by a virtual camera with real images captured by the realworld camera, as well as duplicate properties of the real world cameraand lens. At step 450, a real world image is input and at step 455 thelens and camera characteristics that photographed the real world imageare input to the system. At step 460 a digitally simulated model of acamera and lens is generated based upon the input lens characteristics.At step 465 a computer generated image in the field of view of themodeled camera or data representative of the same is generated. In thisembodiment, the system allows the virtual camera of the computergraphics modeling environment to more closely conform to the real worldcamera.

The system of the present invention also enables the animation ofparameters that are typically not animatable. On a typical real cameraand lens device, some parameters can be changed on a routine basis, forexample, focus, while other things cannot be changed because of physicaland mechanical limitations, such as the size of the film gate(aperture). Because the system of the present invention provides asimulated environment that is not constrained by mechanical physicallimitations, it allows for the animation of parameters that typicallyare considered unanimatable.

At first glance, it would appear that such a feature would not provideany useful ability; however, during an image's life, the image may gothrough many processes, any one of which can cause the aperture oraspect ratio to change. The most typical situation would be if the filmwere scanned or digitized for being input to an image based softwarepackage. If the pictures are altered either through cropping or someother image processing technique, it would be possible to change theapparent aperture size or aspect ratio of the digitally simulated cameraand lens using the system of the present invention. If these values arechanging throughout the course of a motion picture shot, the systemwould cause an animating change in the apparent aperture and/or aspectratio of the images. Thus, the system of the present invention providesthe ability to animate these attributes accordingly to compensate for achange in aspect ratio or film gate pass necessary to correct artifactsthat may result from such an unusual situation.

In addition, based on a portion of the lens parameters input, other lensparameters can be generated. This is illustrated in the flowchart ofFIG. 5. At step 505, at least a subset of camera and lens parametersdesired are input. At step 510, the true lens parameters are generatedbased upon the input.

In an alternate embodiment, the user or a device inputs a basic subsetof parameters, which preferably are correct values, to initialize theprocess. Once the basic subset is input, the system is able to correctthose lens and camera values based upon the relationship of theparameters to each other. Thus, for example, the system may correct afocal length for focus and adjust all necessary derived values, such asreadjustment of the depth of field based on a new derived focal lengthdetermined from focus calculations. Therefore, based on the input, thesystem may adjust a parameter even though a value was input. As thecamera and lens parameters of a real world device can be simulated bythe process, the simulated camera and lens system can be matched to aphysical camera and lens device.

At steps 520, 525, corrected data is output. In one embodiment, thenumeric values are output, step 525, to a display, storage device orother output device or media. Alternately, graphical representations, aswill be illustrated below in subsequent drawings, are generated, step520. In an alternate embodiment, both numeric values and graphicalrepresentations are output, steps 525, 520.

A more detailed flow diagram of the processes utilized in one embodimentof the present invention is illustrated in FIG. 6 a. FIG. 6 b is a tablepresenting a number of the variables that will be referenced in thefollowing discussion. Referring to FIG. 6 a, the input consists of focus605, focal length 610, aspect ratio and film gate (aperture) values 615,infinity setting 620, f-stop and circle of confusion 625. Utilizing thefocus 605 and focal length 610, the true focal length 635 is determined.The true focal length may subsequently be reflected as a number orgraphically presented to the user as will be shown below. To determinethe true focal length, a computation or a look-up table may be used,block 635. In one embodiment, the computation is as follows:TFL=FL+FL ²/(Fo−FL)

where TFL represents the true focal length of the lens, FL representsthe nominal focal length of the lens, and Fo is the distance at whichthe lens is focused, with all values being lengths in consistent unitsof measurement.

Using mathematical equations may be sufficient for some simple lenses.However, very complex lenses, lenses that are of special design, or evenlenses that are out of alignment or unstable may require a measurementand mapping of basic lens properties from which look-up tables may begenerated. This may occur, for example, when a particular type of lensand camera combination is required or some photography has been alreadyshot with a particular type of lens in camera that was not in perfectcondition. Furthermore, it is fairly common for the markings on a lensto be slightly off. For instance, the marks to indicate focus setting ona lens can be off by enough to cause an object to be out of focus if onewere to only go on the lens markings and not look through theviewfinder. Even some lenses that are considered in “perfect”functioning condition simply do not operate according to the normaloptical equations. There are a number of lenses, particularly zoomlenses and those designed for microscopic or macroscopic photographywhose design is fundamentally non-linear. In these cases, changing lensattributes such as focus or the focal length (on a zoom lens) haveunpredictable results. Thus, some mechanism needs to exist to adjust therecorded values so the values correspond to the true optical propertiesof the lens. A look-up table provides a mechanism for incorporatingthose lens peculiarities into the invention's calculations to correctfor these abnormalities.

One advantage to the look-up table is that the table can provide fornon-linear lens characteristics of a particular camera and lens device,thus enabling the system to better match a particular camera and lensdevice. The look-up table in one embodiment may be empiricallydetermined. For example, a look-up table may be configured as follows toinclude empirically determined information:

mark true focal length focus 1 50.2551 inf 2 50.7630 25 3 51.1501 15 451.55 12 5 51.9124 9 6 52.15 7 7 52.683 6 8 52.8815 5 9 53.7263 4 1054.16921 3 11 55.87176 2.5 12 57.136 2

A look-up table may be generated by typically sampling or measuring thechanges in focus and focal length over a range of settings.Interpolation between these measured values is performed to producecorrect lens values between the measured points. These values may thenbe used to provide a more accurate readout of the resulting changes.

A correct vertical field of view 640 and horizontal field of view 645are determined using the aspect ratio and aperture size 615. Thus, inone embodiment, the following computations are performed to determinethe correct horizontal and vertical fields of view.

Vfov = 2 tan⁻¹ ((Ap/Ar)/(2 * TFL)) 638 Hfov = 2 tan⁻¹ (Ap/(2 * TFL)) 643where Vfov represents the vertical field of view, Hfov represents thehorizontal field of view, tan⁻¹ represents an arctangent function, Aprepresents the aperture size, Ar represents the aspect ratio and TFLrepresents the true focal length. The arctangent function may beperformed using a lookup table of values.

The invention may provide clips which serve the same purpose as clipsplaced in the viewfinder of a real camera. The virtual clip provided bythe invention may be a rectangle placed in the 3D graphic modelingenvironment attached perpendicularly at the center of the rectangle tothe optical axis of the virtual camera. The rectangle of the virtualclip has the same aspect ratio as the film gate and a clip width, whichmay be the same size as the film gate aperture of the camera.

The invention may also provide reference objects which are 2 dimensionalobjects that define points of reference within the film gate aperture.The reference objects may be placed on the same plane as the clip andlocated relative to the clip rectangle. The reference objects may be thesize that they will appear in the final rendered image or in aproportional size. It may be convenient to keep the proportionalrelationship between reference objects and their size in the finalrendered image the same as the proportional relationship between therectangle of the virtual clip and the size of the film gate. If the sameproportions are used, reference objects will appear in the same plane asthe clip. There may be situations where reference objects and the clipdo not use the same proportion. In these situations the reference objectand the clip will be in different parallel planes, all of which areattached perpendicularly to the optical axis of the virtual camera.

The clip and the reference objects are placed at a distance from thevirtual camera that is varied as the parameters of the camera areadjusted so that the view from the point of view of the virtual cameraprovides the same visual effect as clips and reference objects in theviewfinder of a real camera. If the clip rectangle is the same size asthe film gate aperture, then the clip must be placed the same distancein front of the nodal point (optical center) of the camera lens as thedistance from the nodal point to the film plane. This distance is thetrue focal length. Therefore a clip that is the same size as the filmgate is positioned according to the following formula:Clip Pos=TFL/25.4where Clip Pos represents the distance from the camera in inches and TFLrepresents the true focal length in millimeters. Using the true focallength 635 determined, three dimensional clips or charts 650 can beplaced a certain distance from the camera and subsequently can beconsistently located regardless of other changes to lens parameters.This information is used to provide visual feedback 650 to the user inthe form of a graphical display of an image with the three dimensionalclips and charts superimposed over the image relative to the particularfield of view determined or lens parameter values 655.

A clip that is proportionally sized is positioned according to thefollowing formula:Clip Pos=(TFL/25.4)*(Clip Width/Ap)where Clip Width represents the width of the clip in inches and Aprepresents the width of the film gate aperture in inches. In oneembodiment, the clips are one inch in width and positioned according tothe following equation:Clip Pos=(TFL/25.4)/Ap

Reference objects are positioned in front of the camera as distancesdetermined as described above except that the proportion betweenreference objects and their size in the final rendered image is used:Ref Pos=(TFL/25.4)*(Ref Width/Img Width)where Ref Pos represents the distance from the camera in inches, TFLrepresents the true focal length in millimeters, Ref Width representsthe width of the reference object in inches, and 1 mg Width representsthe width of the reference object image in inches.

The hyperfocal distance 660, is determined from the focus value 605input, the circle of confusion 625, and the true focal length 635determined. In one embodiment, the hyperfocal distance may be determinedaccording to the following:Hd=(TFL ²)/(Fs*Coc)  658where Hd represents the hyperfocal distance, TFL represents the truefocal length, Fs represents the f-stop, and Coc represents theacceptable diameter of the circle of confusion.

Using the hyperfocal distance 660, the hyperfocal focus may bedetermined as:Hf=Hd*0.5  668

The hyperfocal distance 660 is used to determine the depth of field 675,in particular, far focus and near focus. In one embodiment, the farfocus and near focus is determined as follows:

Nf = (Hd * Fo)/(Hd + (Fo − TFL)) 673 Ff = (Hd * Fo)/(Hd − (Fo − TFL))725 (FIG. 7)where Nf represents the near focus, Ft represents the far focus, Forepresent a focus distance, Hd represents the hyperfocal distance, TFLrepresents the true focal length.

It is possible to calculate a hyperfocal distance from a near focus, afar focus, and a nominal focal length:Hd=((FL/Nf)+(FL/Ff)−2)/((1/Ff)−(1/Nf))where Hd represents the hyperfocal distance, FL represents the nominalfocal length, Nf represents the near focus, and Ff represents the farfocus. This may allow the focus and f-stop to be approximately set bysetting the desired near and far focus points:Fo=(Hd−FL)/((Hd/Nf)−1)Fs=(FL*FL)/(Hd*Coc)where Fo represent a focus distance, Fs represents the f-stop, and Cocrepresents the acceptable diameter of the circle of confusion.

The f-stop setting can be set more exactly by using the Fo determinedfrom the near focus, the far focus, and the nominal focal length todetermine the true focal length (TFL) as previously described. The truehyperfocal distance (THd) is then determined from the TFL:THd=((TF/Nf)+(TFL/Ff)−2)/((1/Ff)−(1/Nf))This may allow the focus and f-stop to be more exactly determined:Fo=(THd−TFL)/((THd/Nf)−1)Fs=(TFL*TFL)/(THd*Coc)

A computer graphics environment is not typically bounded by the normalconstraints of the physical real world. Therefore, an object can be ofnearly any size and any distance from the camera. However, this can leadto problems when dealing with objects or calculations that can often goto infinity such as the focus characteristics.

For example, a number of situations arise where a particular focussetting and f-stop yield a far focus setting that is essentially set atinfinity. This causes the far focus marker to shoot off to someastronomical distance from the camera in a simulated camera program;this is neither desirable nor does it provide any valuable information.In addition, some 3D software programs include a feature thatautomatically shifts the view or camera so all objects are in frame atone time. Thus, if an object is off at infinity, the top view in thethree dimensional software will also scale back to an astronomicaldistance in order to try and “see” all the objects at once.

Unfortunately, if this happens, these view cameras move so far away thateven large objects turn into small specs on the screen. The resultanteffect is that valuable information is lost as the view moves back toinclude the far focus marker which is far away. Thus, in one embodimentof the system of the present invention, the user is able to “setinfinity”. The setting for infinity defines the far bounds of the areainterest. The user can work at a reasonable scale with a user definedboundary or area while still gaining all the benefits of themathematical calculations and feedback from the markers within thatbounded area.

This feature is valuable in a variety of situations, but it isparticularly valuable when dealing with simulations, miniatures andmodels where the area of concern is very small. In this case, seeing allthe markers requires careful setup of side, top and front views of thecamera and focus marker positions and having a setting for infinityhelps preserve these views. Using the infinity setting allows a FinalFar Focus (FinFf) to be calculated that may be used in place of the truefar focus (Ff) to avoid the undesirable effects of placing markers toofar from the virtual camera.

One embodiment of the process for determining the Final Far Focus isillustrated in FIG. 7. The infinity setting 620 may be a single numberset by the user in order to define the limits of the area of interestfrom the camera as a base point. Therefore, if the user sets theinfinity setting to 10 feet, then all reference objects controlled bythe invention will be restricted to movement within 10 feet of thecamera. No markers or other objects controlled by the invention will beallowed to go beyond 10 feet in any direction from the camera. If theuser decides to change the infinity setting to 100 feet, everything isrecalculated and all markers controlled by the invention will berestricted to a placement within 100 feet of the camera. This allows theuser to restrict the invention's markers to a desirable range in orderto limit their movement.

Using the focus (Fo) 605, infinity setting 620, the hyperfocal distance660 and true focal length 635 an initial far focus (Ff) may bedetermined:Ff=(Hd*Fo)/(Hd−(Fo−TFL))  725

If the far focus exceeds the infinity setting 735, then the far focus isset to the infinity setting value 740. If the far focus does not exceedthe infinity setting and the far focus is less than the hyperfocal focus745, then the final calculated far focus value (FinFf) is set to beequal to the far focus value 750. Otherwise, the final focus value isset to the infinity setting 755.

Embodiments and uses of the present invention will be explained usingthe following figures. In one embodiment of the system of the presentinvention, it is contemplated that the values determined are generatedas numerical values for a simplified presentation. In other embodiments,a graphical display is generated; sample graphical display images areillustrated in the following figures.

Referring to FIG. 8 a, a three dimensional perspective view of basiccamera and lens parameters is illustrated. The current view includes acamera body 802, and lens 804. Immediately in front of the lens is asmall rectangle 806; an arrow 808 points to the center of the rectangle806. This is a 3D reference marker which is viewed by the camera 802. Inthis embodiment, the 3D reference marker includes the numbers “2.35”which indicate that it is a 2.35 aspect ratio marker. The largerrectangle 810 is the near focus marker which identifies one end of anacceptable focus towards the camera. In the one embodiment, the lettersNF (near focus) are associated with the rectangle both horizontally andvertically for easy reference. Beside the letters and on top of the nearfocus marker rectangle, there is an arrow 811 pointing to the actualfocus point setting 812. The tip of the arrow is exactly at this pointof focus. Also included is a far focus marker (FF) 814. This is similarto the near focus marker that defines the other end of acceptable focustowards the camera, and also includes an arrow 816 which points to theactual focus point 812. It should be noted that although the two arrows811 and 816 are slightly offset from each other, they both point exactlyto the same place in space, the actual user set point of focus 812. Thevalues for the near focus marker and far focus marker are calculatedfrom this point 812. Also illustrated is a hyperfocal focus point 820.In addition, another arrow 825 points to the location of the hyperfocaldistance 824.

In one embodiment of the system of the present invention, these markersmay be instantly updated whenever an associated lens or camera parameterchanges. For example, the markers will change with corresponding changesin f-stop or focus. Thus, the markers will shift towards the camera oraway from the camera appropriately and can be viewed from a variety ofangles, either through the camera or from another point of view.

FIG. 8 b shows the same scene as FIG. 8 a, but the camera body has beenremoved and a reference grid 830 has been placed on the floor. Forpurposes of discussion, the grid illustrated in the Figures is includedas a visual guide to better orient the viewer's perspective, to note thechanges in the position of the markers as various lens parameters arechanged, and to help understand the 3D relationship of the camera, lensand marker objects as shown in the different views.

In the embodiment illustrated by FIG. 8 b, the camera markers areattached to the camera and travel with the camera; therefore, no matterwhat direction the camera faces, or where it moves, the markers stay incorrect orientation to the camera and lens.

FIG. 8 c shows the camera point of view for the scene of FIGS. 8 a and 8b. It should be noted that the aspect ratio or marker (2.35) is centeredin the lens' field of view, whereas the depth of field is defined by thenear focus and far focus markers. A top orthographic view can also begenerated in the present embodiment. This is illustrated in FIG. 8 d.

FIGS. 8 a-8 d show the same scene from three different view points. Inthis example, the user has set the focal length to 19 mm and the focaldistance is set to four feet with an f-stop of f2.8. Because focusaffects focal length, the focal length, in accordance with the teachingsof the present invention, has been recalculated to the true focal lengthof 19.3008 mm. The values for the hyperfocal distance, hyperfocal focus,near focus, far focus and the 3D reference chart position also arecalculated to provide the correct relationship among the parameters.

FIG. 9 a shows a wide scale top view with special reference lines toindicate the actual camera field of view 905, 910. The angle of viewlines 915 represents the exact edges of the camera's view. It should benoted that the 3D reference chart 920 exactly fits in the angle view atits distance from the lens. The chart does not extend beyond the angleof view lines, and does not fall short of the angle of view lines. Thechart's three dimensional position from the camera is calculated to fitexactly in the field of view so that the reference charts always stayvisually in the same place when viewed through the lens even though thelens values are changing. Thus, the chart is moved to compensate andmaintain an exact steady position relative to the camera field of viewsuch as a physical chart would do when physically attached to a cameraand lens device.

A one foot by one foot cube 925 is placed in the distance for comparisonwith other camera points of view. In FIG. 9 c the focal length is veryshort (e.g., a wide angle lens is used). Thus, the cube 925 appears verysmall.

FIG. 9 b is a perspective view of the scene of FIG. 9 a, showing the 3Dreference chart 920, the near focus 940 and far focus 945, defining thefield of view, and the hyperfocal distance 950. FIGS. 9 c and 9 dprovide a camera view of the scene of FIG. 9 a. In particular, FIG. 9 cshows a 1.5 aspect ratio chart wherein the text marker is turned off andthe Motion Picture Industry's standard 22 field chart (VISTAVISION) issubstituted in the place of the 2.35 chart. FIG. 9 d shows a 2.35 aspectratio 3D reference chart 910.

Thus, it can be seen that the charts are interchangeable and follow thesame rules of placement and orientation regardless of which chart ischosen.

FIGS. 10 a through 10 c illustrate a scene with the f-stop set to f5.6.Comparing FIGS. 10 a-10 c to 9 a-9 c it can be seen that the focallength has not changed and the reference chart position has not changedbecause the focal length has not changed. However, lens parameters basedon the f-stop have changed. These include hyperfocal distance,hyperfocal focus, near focus and far focus. For example, by comparingFIGS. 10 c and 9 c it can be seen that the apparent size of the nearfocus marker in FIG. 9 c occupies a much smaller part of the camerafield of view than it does in FIG. 10 c. This is because the near focusmarker has been calculated to be much closer to the camera with a muchlarger f-stop in FIG. 10 c. Similarly, the far focus marker is furtheraway from the camera in FIG. 10 c compared to FIG. 9 c. These changesand values demonstrate several simultaneous changes in focus parametersas only one value has changed, in this case the f-stop.

FIGS. 11 a through 11 d illustrate the change in the focus distance. Inthis situation, the parameters are set to the same as shown in FIGS. 9 athrough 9 d, but the focus has been changed from four feet to ten feet.Because the focus is changing, the focal length changes accordingly. Inthis situation, focusing further away from the camera results in a focallength that is slightly shorter; thus, the calculated true focal lengthequals 19.1192 mm, while at four feet it was 19.3008 mm. Visually, thedifference can be seen by comparing FIG. 9 b with FIG. 11 a. FIG. 9 bhas a focus of four feet, and FIG. 11 a has a focus of ten feet.

It should be noted that the hyperfocal distance and hyperfocal focus andthe 3D reference marker position have only changed very slightly due tothe very slight change in focal length from the affected focus. However,the positions of the near and far focus have changed dramatically due tothe focus being set further away from the camera.

In FIG. 11 a the perspective view of the camera and lens markers havebeen moved back a significant amount in order to show the far focusmarker being so far away from the camera. Also, it should be noted thatin FIG. 11 a, the arrows coming from the near focus marker and far focusmarker still point to the same position space as the actual focussetting of ten feet. As noted earlier, these marker arrows expand inaccordance with the positions of the tails set at the marker positionsand the tips of the arrow stay at the user focus set point.

The changing angle of view can be seen by comparing FIGS. 9 a and 11 b.The angle of view change is slight; however, by comparing the locationof the angle of view with respect to the grid in the two figures aslight change of position can be seen. The change is due to a veryslight change of focal length between a four foot setting and a ten footsetting on a 19 mm lens. These types of changes, although very small,are what lead to problems in the prior art when attempting to alignimages when the focal length has not been correctly calculated to takeinto the account the effects of focus.

FIGS. 12 a through 12 c show a different camera and lens setup in whicha 100 mm lens is set to a ten foot focus and f-stop of F2.8. FIG. 12 ais a top orthographic view. It can be seen that two arrows point exactlyto the ten foot line on the grid. It should also be noticed that the 3Dreference chart has been moved up to 2.7861 feet in front of the lens,whereas the position for the 19 mm lens setup (e.g., FIGS. 9 a through 9d) was a little over a 0.5 feet. This is because the angle of view hasbecome very narrow and to fit the angle of view exactly, the 3Dreference chart must be pushed out further beyond the lens to correctlybe represented in the camera field of view. This effect also can be seenreferencing FIGS. 12 b and 12 c. In FIG. 12 b, the 3D reference chart1250 is far beyond the lens 1255. The near and far focus markers (notvisible) are positioned approximately ten feet beyond the lens. Thus,referring to FIG. 12 b it can be seen that the much longer focal lengthlens results in fixed cube 1265 becoming much larger in frame (rowpositioned roughly between the left “2” and “4” markers on the numberedgrid) compared to the cube in FIG. 11 d. The cube in FIG. 11 d is thevery small square 1122 to the left of the center zero mark; thisillustrates the effects of the changing focal length.

FIGS. 13 a and 13 b show the effect of changing the focus to twenty feetwhile keeping the other parameters the same. The near focus and farfocus markers are positioned with the tips of the markers located atexactly twenty feet. The depth of view is barely one foot on eitherside. However, near focus and far focus markers appear very large inFIG. 13 b. They are actually very far away as shown in FIG. 13 a.

FIGS. 14 a and 14 b show the effect of changing the f-stop from f2.8 tof16. By increasing the f-stop to f16, the near and far focus areexpanded much further away from each other resulting in a much greaterdepth of view. The arrows of the markers still point to the twenty footmark which is a user set focus setting. As the f-stop is changed by theuser, the lens parameters automatically are updated and positionedcorrectly. It should be recognized that throughout the examples shown,whenever a reference chart, such as the numbered grid, is seen throughthe camera, it usually appears absolutely the same regardless of thefocal length or other changes, as if there were a fixed object attachedto the camera eye piece aperture, just like a physical chart that ismechanically attached to a real world camera. As discussed above, theeffect is achieved by calculating dynamically the reference chartposition in order to reverse the effects of the changing focal length.Thus, the reference chart appears unchanging to the user and camerapoint of view while it is actually changing its position in the 3D worldto simulate the static effect. Visually this effect is illustrated bycomparing FIGS. 12 c and 9 c. Although the near focus and far focus andother markers are moving, the reference clip does not appear to changeposition in the camera point of view even though its position isdrastically different.

While certain exemplary embodiments have been described and shown in theaccompanying drawings, it is to be understood that such embodiments aremerely illustrative of and not restrictive on the broad invention, andthat this invention not be limited to the specific constructions andarrangements shown and described, since various other modifications mayoccur to those ordinarily skilled in the art.

1. A computerized method for visualizing a setting of a virtual cameraand lens system in a three dimensional computer graphic modelingenvironment, the method comprising: receiving a nominal focal length anda focus distance for the virtual camera; calculating a true focallength; providing an optical axis object that represents the opticalaxis of the virtual camera and lens system in the three dimensionalcomputer graphic modeling environment; and attaching an object to theoptical axis at a location that represents the setting of the virtualcamera and lens system as determined from the true focal length.
 2. Themethod of claim 1 wherein the setting of the virtual camera and lenssystem is one of a field of view, a hyperfocal distance, a hyperfocalfocus, a near focus, a far focus, a clip, or a reference object.
 3. Themethod of claim 1 wherein the true focal length is calculated accordingto the formula ofTFL=FL+FL ²/(Fo−FL) wherein TFL represents the true focal length, FLrepresents a nominal focal length, and Fo is a distance at which thelens is focused, with all values being lengths in consistent units ofmeasurement.
 4. The method of claim 1 wherein the setting of the virtualcamera and lens system is one of a field of view or a clip, and theobject is a rectangle having a width of Clip Width and a center that isattached perpendicularly to the optical axis at a distance of Clip Posfrom the virtual camera and lens system, where Clip Pos is calculatedaccording to the formula ofClip Pos =(TFL)*(Clip Width/Ap) where TFL represents the true focallength, Clip Width represents the width of the clip, and Ap representsthe width of the film gate aperture, with all values being lengths inconsistent units of measurement.
 5. The method of claim 1 wherein thesetting of the virtual camera and lens system is a hyperfocal distance(Hd), and the object is a marker attached to the optical axis at adistance of Hd from the virtual camera and lens system, where Hd iscalculated according to the formula ofHd=(TFL ²)/(Fs*Coc) where TFL represents the true focal length, Fsrepresents an f-stop, and Coc represents an acceptable diameter of acircle of confusion, with all values that are lengths being inconsistent units of measurement.
 6. The method of claim 1 wherein thesetting of the virtual camera and lens system is a near focus (Nf), andthe object is a marker attached to the optical axis at a distance of Nffrom the virtual camera and lens system, where Nf is calculatedaccording to the formula ofNf=((TFL ²/(Fs*Coc))*Fo)/((TFL ²//(Fs*Coc))+(Fo−TFL)) where TFLrepresents the true focal length, Fs represents an f-stop, Cocrepresents an acceptable diameter of a circle of confusion, and Forepresent a focus distance, with all values that are lengths being inconsistent units of measurement.
 7. The method of claim 1 wherein thesetting of the virtual camera and lens system is a far focus (Ff), andthe object is a marker attached to the optical axis at a distance of Fffrom the virtual camera and lens system, where Ff is calculatedaccording to the formula ofFf=((TFL ²/(Fs*Coc))*Fo)/((TFL ²/(Fs*Coc))+(Fo+TFL)) where TFLrepresents the true focal length, Fs represents an f-stop, Cocrepresents an acceptable diameter of a circle of confusion, and Forepresent a focus distance, with all values that are lengths being inconsistent units of measurement.
 8. The method of claim 1 wherein thesetting of the virtual camera and lens system is a far focus (Ff), andthe object is a marker attached to the optical axis at a distance offinal far focus (FinFf) from the virtual camera and lens system, themethod further comprising: receiving an infinity setting (Inf);calculating Ff according to the formula ofFf=((TFL ²/(Fs*Coc))*Fo)/((TFL ²/(Fs*Coc))+(Fo+TFL)) where TFLrepresents the true focal length, Fs represents an f-stop, Cocrepresents an acceptable diameter of a circle of confusion, and Forepresent a focus distance, with all values that are lengths being inconsistent units of measurement; and setting FinFf to Inf if Ff isgreater than Inf, otherwise setting FinFf to Ff.
 9. The method of claim8 further comprising setting FinFf to Inf if Ff is greater than ahyperfocal focus (Hf).
 10. A computerized method for setting of avirtual camera and lens system in a three dimensional computer graphicmodeling environment, the method comprising: receiving a nominal focallength and a focus distance; calculating a true focal length; setting afocal length of the virtual camera and lens system to the true focallength; providing an optical axis object that represents the opticalaxis of the virtual camera and lens system in the three dimensionalcomputer graphic modeling environment; and attaching an object to theoptical axis at a location that represents a setting of the virtualcamera and lens system as determined from the true focal length.
 11. Acomputerized method for visualizing a rendering that results fromsettings of a virtual camera and lens system in a three dimensionalcomputer graphic modeling environment, the method comprising: receivingorientation data for the virtual camera, including position data, tiltdata, pan data, and roll data; setting orientation parameters for thevirtual camera and lens system using the received orientation data, theorientation parameters corresponding to those displayed on an attachedopical axis object that is used to define an area associated with a filmgate; displaying the rendering in the three dimensional computer graphicmodeling environment based on the orientation parameters; receivingupdated orientation data for the virtual camera, including positiondata, tilt data, pan data, and roll data, where at least one of theposition data, tilt data, pan data, and roll data in the updatedorientation data is different from the corresponding position data, tiltdata, pan data, and roll data in the received orientation data; updatingthe orientation parameters for the virtual camera; and displaying arendering in the three dimensional computer graphic modeling environmentbased on the updated parameters of the virtual camera and lens system;wherein the updated orientation data is received from a virtual cameracontrol input device.
 12. The method of claim 11, wherein the updatingthe orientation parameters for the virtual camera is based on adifference between the received updated orientation data and thereceived orientation data.
 13. The method of claim 11, wherein thecontrols of the virtual camera control input device are controlsassociated with a physical digital camera.
 14. The method of claim 11,wherein the controls of the virtual camera control input device includea user input device.
 15. The method of claim 14, wherein the controls ofthe virtual camera control input device include a mouse.
 16. The methodof claim 14, wherein the controls of the virtual camera control inputdevice include a keyboard.
 17. A system for visualizing a rendering thatresults from settings of a virtual camera and lens system in a threedimensional computer graphic modeling environment, the systemcomprising: a rendering system including (i) a display, (ii) a memorystoring orientation data for the virtual camera, including positiondata, tilt data, pan data, and roll data, (iii) a input deviceconnection, and (iv) a processor in communication with the display, thememory, and the input device connection, wherein the processor isconfigured to store orientation data for the virtual camera receivedthrough the input device connection, generate and update a renderingbased on stored orientation data and guided by usage of attached opticalaxis objects, and to display the rendering through the display; and avirtual camera control input device including (i) one or more controlsto control the position and orientation of the virtual camera controlinput device, (ii) a data recorder to record orientation data for thevirtual camera, including position data, tilt data, pan data, and rolldata, and (iii) a connection to the input device connection of therendering system to send the orientation data to the rendering system.18. The system of claim 17, wherein the one or more controls of thevirtual camera control input device are controls associated with aphysical digital camera.
 19. The system of claim 17, wherein thecontrols of the virtual camera control input device include a user inputdevice.